Results 61 to 70 of about 219 (161)

Snow Leopard Permutations and Their Even and Odd Threads [PDF]

Discrete Mathematics & Theoretical Computer Science, 2016
Caffrey, Egge, Michel, Rubin and Ver Steegh recently introduced snow leopard permutations, which are the anti-Baxter permutations that are compatible with the doubly alternating Baxter permutations. Among other things, they showed that these permutations
Eric S. Egge, Kailee Rubin
doaj   +1 more source

A refined enumeration of hex trees and related polynomials

, 2015
A hex tree is an ordered tree of which each vertex has updegree 0, 1, or 2, and an edge from a vertex of updegree 1 is either left, median, or right. We present a refined enumeration of symmetric hex trees via a generalized binomial transform.
Richard P. Stanleyb, Stanley, Richard P, Hana Kim, Kim, Hana, Hana Kima, Richard P. Stanley   +5 more
core   +1 more source

On nested block designs geometry

Orthogonal designs, Orthogonal block structure, General balance, Commutativity of projectors, Commutative quadratic subspace, Primary 62J05, Secondary 05A15, 15A18,
Radosław Kala
core   +1 more source

On a generalization of derangement polynomials and numbers

Demonstratio Mathematica
In T. Kim, D. S. Kim, and D. V. Dolgy, Probabilistic derangement numbers and polynomials, Math. Comput. Model. Dyn. Syst. 31 (2025), no. 1, 2529188, Kim-Kim defined the probabilistic derangement polynomials and numbers and found some properties of those ...
Yun Sang Jo, Park Jin-Woo
doaj   +1 more source

The permutation class Av(4213,2143) [PDF]

Discrete Mathematics & Theoretical Computer Science, 2017
We determine the structure of permutations avoiding the patterns 4213 and 2143. Each such permutation consists of the skew sum of a sequence of plane trees, together with an increasing sequence of points above and an increasing sequence of points to its ...
David Bevan
doaj   +1 more source

Fibonacci Cartan and Lucas Cartan numbers

Open Mathematics
This study introduces Fibonacci Cartan and Lucas Cartan numbers, extending the classical Fibonacci and Lucas sequences into the framework of Cartan numbers.
Öztürk İskender, Çakır Hasan
doaj   +1 more source

Proofs of Conjectures about Pattern-Avoiding Linear Extensions [PDF]

Discrete Mathematics & Theoretical Computer Science, 2019
After fixing a canonical ordering (or labeling) of the elements of a finite poset, one can associate each linear extension of the poset with a permutation.
Colin Defant
doaj   +1 more source

Growing and Destroying Catalan-Stanley Trees [PDF]

Discrete Mathematics & Theoretical Computer Science, 2018
Stanley lists the class of Dyck paths where all returns to the axis are of odd length as one of the many objects enumerated by (shifted) Catalan numbers.
Benjamin Hackl, Helmut Prodinger
doaj   +1 more source

Distribution of sets of descent tops and descent bottoms on restricted permutations [PDF]

Discrete Mathematics & Theoretical Computer Science
In this note, we prove some and conjecture other results regarding the distribution of descent top and descent bottom sets on some pattern-avoiding permutations.
Alexander Burstein
doaj   +1 more source

Enumeration of super-strong Wilf equivalence classes of permutations in the generalized factor order [PDF]

Discrete Mathematics & Theoretical Computer Science, 2019
Super-strong Wilf equivalence classes of the symmetric group ${\mathcal S}_n$ on $n$ letters, with respect to the generalized factor order, were shown by Hadjiloucas, Michos and Savvidou (2018) to be in bijection with pyramidal sequences of consecutive ...
Ioannis Michos, Christina Savvidou
doaj   +1 more source